Di-hydroxyl terminated polyisobutylenes (HO-PIB-OHs) are important intermediates for the synthesis of hydrolytically and oxidatively resistant biocompatible and biostable materials including, but not restricted to, polyurethanes (PUs). Methods for the preparation of HO-PIB-OH and its use for the preparation of hydrolytically-oxidatively resistant PUs are well known; however, the synthesis of HO-PIB-OH is complex and expensive, involving expensive hydroboration and purification steps. At the present the most reliable route to HO-PIB-OH involves isobutylene polymerization initiation by the bifunctional initiator tert-butyl-dicumyl chloride (tBudiCumCl) in conjunction with TICl4, terminating the polymerization with allyltrimethylsilane to yield allyl-telechelic PIB (A-PIB-A), and converting the latter by hydroboration/oxidation to the target HO-PIB-OH. Hydroboration calls for the use of relatively expensive H3B.
Heretofore, such di-hydroxyl terminated polyisobutylenes (HO-PIB-OHs) have primarily focused on obtaining compositions that place the —OH group(s) on the primary terminal carbon, as many times, the —OH groups are susceptible to being positioned on the secondary terminal carbon based upon Markovnikov's Rule, which, for hydroxyl group (OH) bonds, provides that the —OH group will bond to the carbon that has the greater number of carbon-carbon bonds, while the hydrogen bonds to the carbon on the other end of the double bond, that has more carbon-hydrogen bonds. Thus, forcing the —OH groups to bond to the primary carbon in an allyl (—CH2-CH2=CH2) or vinylidene (—CH2—CH(CH3)═CH2) group has been accomplished only at great expense using complex anti-Markovnikov reactions.
Thus, the need exists to provide a simple and inexpensive preparation method that provides for di-hydroxyl terminated polyisobutylenes wherein the —OH groups are on the primary carbon.